diff options
Diffstat (limited to 'arch/x86/kvm/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 81db7d48ab80..e889b768c751 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1721,6 +1721,186 @@ static void vmx_set_gdt(struct kvm_vcpu *vcpu, struct descriptor_table *dt) vmcs_writel(GUEST_GDTR_BASE, dt->base); } +static bool rmode_segment_valid(struct kvm_vcpu *vcpu, int seg) +{ + struct kvm_segment var; + u32 ar; + + vmx_get_segment(vcpu, &var, seg); + ar = vmx_segment_access_rights(&var); + + if (var.base != (var.selector << 4)) + return false; + if (var.limit != 0xffff) + return false; + if (ar != 0xf3) + return false; + + return true; +} + +static bool code_segment_valid(struct kvm_vcpu *vcpu) +{ + struct kvm_segment cs; + unsigned int cs_rpl; + + vmx_get_segment(vcpu, &cs, VCPU_SREG_CS); + cs_rpl = cs.selector & SELECTOR_RPL_MASK; + + if (~cs.type & (AR_TYPE_CODE_MASK|AR_TYPE_ACCESSES_MASK)) + return false; + if (!cs.s) + return false; + if (!(~cs.type & (AR_TYPE_CODE_MASK|AR_TYPE_WRITEABLE_MASK))) { + if (cs.dpl > cs_rpl) + return false; + } else if (cs.type & AR_TYPE_CODE_MASK) { + if (cs.dpl != cs_rpl) + return false; + } + if (!cs.present) + return false; + + /* TODO: Add Reserved field check, this'll require a new member in the kvm_segment_field structure */ + return true; +} + +static bool stack_segment_valid(struct kvm_vcpu *vcpu) +{ + struct kvm_segment ss; + unsigned int ss_rpl; + + vmx_get_segment(vcpu, &ss, VCPU_SREG_SS); + ss_rpl = ss.selector & SELECTOR_RPL_MASK; + + if ((ss.type != 3) || (ss.type != 7)) + return false; + if (!ss.s) + return false; + if (ss.dpl != ss_rpl) /* DPL != RPL */ + return false; + if (!ss.present) + return false; + + return true; +} + +static bool data_segment_valid(struct kvm_vcpu *vcpu, int seg) +{ + struct kvm_segment var; + unsigned int rpl; + + vmx_get_segment(vcpu, &var, seg); + rpl = var.selector & SELECTOR_RPL_MASK; + + if (!var.s) + return false; + if (!var.present) + return false; + if (~var.type & (AR_TYPE_CODE_MASK|AR_TYPE_WRITEABLE_MASK)) { + if (var.dpl < rpl) /* DPL < RPL */ + return false; + } + + /* TODO: Add other members to kvm_segment_field to allow checking for other access + * rights flags + */ + return true; +} + +static bool tr_valid(struct kvm_vcpu *vcpu) +{ + struct kvm_segment tr; + + vmx_get_segment(vcpu, &tr, VCPU_SREG_TR); + + if (tr.selector & SELECTOR_TI_MASK) /* TI = 1 */ + return false; + if ((tr.type != 3) || (tr.type != 11)) /* TODO: Check if guest is in IA32e mode */ + return false; + if (!tr.present) + return false; + + return true; +} + +static bool ldtr_valid(struct kvm_vcpu *vcpu) +{ + struct kvm_segment ldtr; + + vmx_get_segment(vcpu, &ldtr, VCPU_SREG_LDTR); + + if (ldtr.selector & SELECTOR_TI_MASK) /* TI = 1 */ + return false; + if (ldtr.type != 2) + return false; + if (!ldtr.present) + return false; + + return true; +} + +static bool cs_ss_rpl_check(struct kvm_vcpu *vcpu) +{ + struct kvm_segment cs, ss; + + vmx_get_segment(vcpu, &cs, VCPU_SREG_CS); + vmx_get_segment(vcpu, &ss, VCPU_SREG_SS); + + return ((cs.selector & SELECTOR_RPL_MASK) == + (ss.selector & SELECTOR_RPL_MASK)); +} + +/* + * Check if guest state is valid. Returns true if valid, false if + * not. + * We assume that registers are always usable + */ +static bool guest_state_valid(struct kvm_vcpu *vcpu) +{ + /* real mode guest state checks */ + if (!(vcpu->arch.cr0 & X86_CR0_PE)) { + if (!rmode_segment_valid(vcpu, VCPU_SREG_CS)) + return false; + if (!rmode_segment_valid(vcpu, VCPU_SREG_SS)) + return false; + if (!rmode_segment_valid(vcpu, VCPU_SREG_DS)) + return false; + if (!rmode_segment_valid(vcpu, VCPU_SREG_ES)) + return false; + if (!rmode_segment_valid(vcpu, VCPU_SREG_FS)) + return false; + if (!rmode_segment_valid(vcpu, VCPU_SREG_GS)) + return false; + } else { + /* protected mode guest state checks */ + if (!cs_ss_rpl_check(vcpu)) + return false; + if (!code_segment_valid(vcpu)) + return false; + if (!stack_segment_valid(vcpu)) + return false; + if (!data_segment_valid(vcpu, VCPU_SREG_DS)) + return false; + if (!data_segment_valid(vcpu, VCPU_SREG_ES)) + return false; + if (!data_segment_valid(vcpu, VCPU_SREG_FS)) + return false; + if (!data_segment_valid(vcpu, VCPU_SREG_GS)) + return false; + if (!tr_valid(vcpu)) + return false; + if (!ldtr_valid(vcpu)) + return false; + } + /* TODO: + * - Add checks on RIP + * - Add checks on RFLAGS + */ + + return true; +} + static int init_rmode_tss(struct kvm *kvm) { gfn_t fn = rmode_tss_base(kvm) >> PAGE_SHIFT; |